Method of splicing rubber articles



Feb. 17, 1942. .1. F. CAMPBELL ET AL 2,273,464

METHOD OF SPLICING RUBBER ARTICLES 5 Sheets-Sheet l Original Filed Feb. 4, 1939 llll Jerome hy/e/h J. F. CAMPBELL ET AL METHOD OF SPLICING RUBBER ARTICLES Feb. 17, 1942.

Original Filed Feb. 4, 1959 5 Sheets-Sheet 2 F J. F. CAMPBELL ETAL 2,273,464 .METHODOF SPLICING RUBBER ARTICLES Original Filed Feb. 4, 1939 5 SheetsSheet 3 v 6 my 11 .7 JMHFoW M/M 7:2 de ame F/P/Yy/e/h (heal-Value F .17,1942. J. F. CAMPBELL Em 2 273,4

METHOD OF SPLICING RUBBER ARTICLES Original Filed Feb. 4, 1939 5 Sheets-Sheet 4 (jealrah/e 42 V Raga/off;

- Check. Valve Feb. 17, 1942. v J. F. CAMPBELL ET AL 2,273,464

METHOD OF SPLICING RUBBER ARTICLES Original Filed Feb. 4, 1939 5 Sheets-Sheet 5 158 75 Empemare Corrro/ (/n/ :lavuc/Mow Mot/wa the plane of the material.

Patented Feb. 17 1942 METHOD OF SPLICING RUBBER ARTICLES John F. Campbell, Cuyahoga Falls, and Jerome F.

Ringlein, Akron, Ohio, assignors to Wingfoot Corporation, Wilmington, Del., a corporation of Delaware Original application February 4,

1939, Serial No.

254,722. Divided and this application April 25,

g 1940, Serial No. 331,576

'7 Claims.

invention relates .to improvements in methods of splicing rubber articles, and it refers A .more particularly to such methods for use in join ing ends of unvulcanized inner tube and tread stock. This application is a division of application Serial No. 254,722, filed February 4, 1939.

Prior to this invention, unvulcanized inner tube and tread stock has beenspliced by the methods and machines disclosed in U. S. Letters Patent Nos. 2,024,577; 2,024,578; and 2,040,466. While those methods and'machines have been extensively used with great commercial success, they are improved by the present invention. In practicing the inventions of the above-enumerated patents, two ends of the inner tube stock or the tread stock, as the case may be, are clamped flat in a pair of alined clamping devices, and while so held, said ends are cut ofi transversely andheated. Thereafter the freshly cut ends are brought forcibly together and joined preparatory to vulcanization. The cutting has been done with heated knives traveling in a straight line, the a heat from the knives enhancing the tackiness of the stock to insure a good union. Instead of ef-' I fecting a transversely straight cut as in the prior be betterappreciated. The cutting-may be done with knives which preferably are heated to a predetermined temperature and,-by changing the line of cut during the cutting operation, these heated knives are less likely to sear the rubber and therefore they leave the freshly cut ends of the rubber in better condition for splicing. After the cutting operation has been completed the clamps are moved toward each other in such a way as to force the freshly cut ends of rubber into progressive mutual contact forming a perfect splice without any air being trapped between the joined surfaces. The pressure with which the ends of the rubber are brought together is sumcient to leave slight fins of excess material surrounding the splice,-this excess material further advantages of the invention will be-fully appreart, the present invention contemplates substantially oblique cuts or off-set cuts, so that when the cut ends are brought together they will first contact at one edge, and continued pressure will result in progressive contact without entrapping any air between the joined surfaces. Preferably suflicient pressure is exerted toform fins of excess material around the joint, thus giving greater strength thereto.

One of the objects of the invention is to provide a novel method for cutting the ends of the rubber stock to effect the improved splice or joint referred to above.

Another object of the invention is to provide a complete splicing method which includes the novel method steps.

More specifically. the invention contemplates completely flattening and holding fiat the ends of the tube stock or tread stock to be spliced and cutting portions from the ends so held, the line of out being generally oblique with reference to In one form of the invention the material is held flat in a pair of clamps which are movable toward and from each other and, by moving said clamps slightly away from each other during the cutting operation, the line of the cut is changed. In one respect this effects a combined cutting and tearing action on the rubber and it provides a certain amount of excess material for the splice, as will hereina ter position but without showing any ciated from the following description in connection with the accompanying drawings, wherein the method has been illustrated diagrammatically and one form of apparatus has been shown. for

,practicing the method. In the drawings:

elevation of the improved splicing machine with the parts shown in their re-' Fig. 1 is a front spective positions at the beginning of the cycle of operations.

Fig. 2 is a'fragmentary viewon a larger scale partly in section and partly in elevation, the view being taken approximately on line 2-2 of Fig.1. Fig. 3 is a complete elevation of one side of the machine with the clamping means in clamping stock being operated upon. Fig. 4 is a rear view thereof. 1 Figs. 5-11, inclusive,.are fragmentary diagrammatic views similar to each other but illustrating successive steps in the novel method of splicing.

\Fig. 12 is a diagrammatic view of the various fluid pressure cylinders and controlling meanstherefor, and

Fig. 13 is a wiring diagram of the electrical connections for the machine. 7

Referring first to Figs. 5 to 11, inclusive, the

method will be described and it is to be understood that various forms of apparatus may be employed for practicing such method. In the illustrated embodiment bers l5, l6 and l1, l8, said clamping members the ends'T'--l and T-2 I of unvulcanized rubber tube stock are flattened and held respectively between clamping mem-' and I1 and directly below the protruding ends of the rubber tube stock. Cutting means such as a pair of knives 20 are moved downwardly toward the anvil I9 with their sharp ends entering the upper flattened wall of the tube stock. After ther knives 20 have penetrated the tube stock a predetermined distance substantially equivalent to that shown in Fig. 5, their downward movement is interrupted and, while so interrupted, the clamping members I5 and I1 and their associated parts are moved away from each other a very slight distance. To a certain extent this action either tears or distorts the rubber as illustrated in Fig. 6. Thereafter the downward movement of the knives 22 continues entirely through the rubber as shown in Fig. 7, thus removing from the extremities of the tube stock small portions 2| .which are not needed and exposing freshly cut surfaces 22 and 23 which are subsequently to be joined. After the cuts-are thus completed the clamping members move farther apart so as to completely disengage the rubber from the knives as shown in Fig. 8 and thereafter the knives return upward while the anvil 9 moves downward. It is to be noted that the freshly cut surfaces 22 and 23 of the rubber stock are substantially oblique with reference to the flattened plane of the tube stock, and this is important in effecting a perfect splice. While the tube stock is still held in flattened condition, the end surfaces 22 and 23 are brought forcibly together as shown in Fig. 10. Due to the obliquity of the end surfaces contact will first be made adjacent the lower edges of the stock and there- 'after continued force or pressure will bring the surfaces 22 and 23 progressively into mutual engagement in such a way-as to prevent entrapping of air between such surfaces. Preferably the ends of the tube stock are pressed together sufficiently to form fins 24 of excess material surrounding the joint as shown in Fig. 11. The ends of the tube stock thus pressed together become perfectly united by reason of theirvtacky condition and they remain so united in subsequent handling, and they become completely mergedin vulcanization.- Incidentally'when the tubes s0 spliced are vulcanized in a confining mold, as is customary, the fins 24 of excess material substantially disappear by reason vof the flow ,of heated rubber inwardly from the mold surface, some of such excess rubber distributing itself in the wall of the tube and some remaining to form a slight bulging portion on the interior of the tube and surrounding the splice.

Experience has shown that splices made by this method aresuperior to those of the prior patents previously referred to and that they can easily be carried out in large production schedules with a minimum number of defects. It is to be noticed that when the ends-are severed by a combined cutting and tearing action, as illustrated in Figs. 5, 6 and "I, the first-cut portions of the surfaces 22 and 23 are quickly moved away from the knives 25 likely to become seared as would otherwise be the case when the knives are heated. The nature of the rubber is such that the line of out .can easily be changed, as has been described, but obviously the method may also be practiced by moving the knives in oblique paths-rather than perpendicular to the clamped rubber stock- When splicing inner-tube stock the interior of the tube stock is quite heavily dusted with soapstone or other material to prevent the rubber walls from adhering to' each other and when method is used with the offset out above describedit is preferable to make the ofiset bethe carriages and 3| fore the knives have gone entirely through the first wall of rubber. Thus, as they pass through the layer of soapstone between the superimposed faces of rubber, the knives will not disturb the soapstone sufliciently to interfere with the tackiness of the end below said layer of soapstone. Itis of course to be understood that, while the method has been illustrated and described particularly in reference to splicing inner-tube stock, it is equally adaptable and effective for splicing other rubber material, such as tread bands for use in manufacturing pneumatic tires. I One form of apparatus for practicing the above-described method is illustrated in Figs. 1-4, inclusive, such apparatus including the prin-- cipal features of the above-identified patents,

together with certain additional features which are of the essence of the present invention. In these views of the drawings it will be seen that the lower clamping members l5 and I1 are respectively arranged upon a pair of alined carriages 30 and 3| which are mounted for movement endwise toward and from each other on dovetailed guides 32 and 33. The upper clamping members l6 and I8 are also arranged upon so as to be bodily movable therewith but they are pivoted as at 34 to facilitate their movement into and out of clamping positions. Preferably the clamping members It and 8 comprise a multiplicity of yieldably mounted metal plates which at least partly en--v circle an inflatable core or airbag, the construction being substantially the same as that described and claimedin the Christy Patent 2,040,466. Clampsof this type are quite flexible and thus they conform readily to the contour of the particular material which is being operated and thus they are notxso upon in the machine. Lever arms 35 and 36 extend rearwardly from the upper clamping members l6 and I8 for swinging movement about the pivotal connection 34, whereby to actuate said clamping members. The rearward ends of said lever arms ,35 and 35 are respectively connected at 31 and 38 with the lower ends of piston rods 39 and 40 which carry pistons operable within fluid pressure cylinders 4| and 42. These fluid pressure cylinders have their upper ends pivoted at and 44 to a pair of goose-neck extensions 45 and 46 which rise from the rearward sides of the carriages 30 and 3|. By admitting pressure fluid alternately to opposite ends of the cylinders and 42 the lever arms 35 and 36 are caused to rock or swing about the pivotal connection 34 to raise and lower-the upper clamping members It and I3. In order to actuate the carriages 30 and 3| for movement toward and from each other there are provided a pair 01" rack bars 48 and 45 which may be attached to or integral with the lower portions of the car-' riages. These rack bars are constantly in mesh with pinions 50 and 5| which are mounted for rotation with and by gears 52 and 53, said gears being mounted at the rearward side of the machine and being constantly in mesh with a double-face rack bar 54 disposed between them. The rack bar 54 is movable upwardly and downwardly by reason of its connection with a piston rod 55 which extends into a pressure cylinder 55 and wherein there is a piston attached to the end of said piston rod 55. As pressure fluid is admitted alternately to opposite ends of the cylinder 56, the double-face rack bar 54 is caused to move longitudinally, rotating the gears 52 and sa and the pinions so and 5|, and as the pinions thus rotate the carriages 36 and 31 and their associated parts are caused to move either toward or away from each other, dependent upon which end of the cylinder 56 has the pressure in it. I 1

The anvil I9 (best shown in Fig. 1) comprises a relatively flat metallic block or plate which is movable upwardly and downwardly into and out of the path of relative movement of the clamping members l5 and I1. When the anvil is in its uppermost position it is disposed between the ends of the clamping members l5 and I! and directly below the protruding ends of the stock clamped therein, and it is so proportioned as to give support to the clamped ends of the stock when said stock is being operated upon by the knives 26. The anvil-l8 is mounted upon the upper end of a piston rod 59, the lower end of which extends into a pressure cylinder 60 wherein there is a reciprocating piston of any ordinary or preferred form. As pressure fluid is admitted to the lower end of said cyiinder 60 the anvil is raised and as such pressure is released from the lower end of the cylinder the anvil is moved downwardly out of the 'path of the lower clamping members and carriages.

The knives 26 having sharpened lower cutting edges are mounted above the clamping members upona slide 62 which slide is guided for vertical movement in an upward extension 68 of the machine frame. This extension 63, as well as the parts previously described, are supported upon a suitable frame or base 64 of any preferred form. The slide 62 is appropriately secured to the lower end of a piston rod 65 which extends into a pressure cylinder 66 wherein there is another reciprocating piston for actuating the piston rod. The pressure cylinder 66 is fixed to the frame extension 63 substantially in the vertical center line of the machine and below another pressure cylinder 61 which is supported upon a fixed cross bar 68 adjacent the top of the frame. Within the cylinder 61 there is a piston attached to an upwardly projecting piston rod 69 which is disposed in the path of movement of an adjustable abutment 16 which also has associated with it an extension H adapted at certain times to strike against and to actuate a normally open micro switch 12. The

abutment "I0 and the extension 'H are carried on a cross arm 13 secured-to the upper end of a pair of sliding rods '14 which are suitably guided in the upper portion of the frame and secured to the slide 6'2.

When the cutting knives 26 are in their uppermost position (inactive) the abutment 16 and its associated parts are also in their uppermost positions and thus held by fluid pressure in the lower end of cylinder 66. At the same time fluid under pressure is present in the lower end of cylinder 61. When it is desired to lower the knives for the cutting operation pressure is'released from the lower end of cylinder 66 and admitted to the upper end of said cylinder, thus causing the slide 62 and its associated parts, including the rods I4 to move downwardly toward the anvil l9. In the course of such movement the abutment 16 will come into contact with the projecting end of the piston rod and this will temporarily stop the descent of the knives. At substantially the same time the extension 1l' will contact the micro switch 12, closing an electric circuit therethrough to energize a solenoid which controls a normally open three-way valve 16. As the valve "is thus actuated the pressure fluid is slowly released from the lower end of cylinder 61 through a suitable conduit l1 and regulating check valve 18. As this occurs the slide 62 and its associatedparts is free to move downwardly again under the pressure exist-- ing in the upper end of cylinder 66 until the knives 26 complete their movement entirely through the rubber held in the clamping mem- .bers l5, I6, l1 and I8.

for abutment with the upper end 84 of the rack bar 54. Similarly the upper end 85 of the piston rod 82 is adapted for abutment at certain times with the lower end 86 of a piston rod 61 which extends into the cylinder 8| for connection with a piston therein. Under certain conditions the end portions 85 and 86 are out of contact with each other but in other conditions they are in mutual contact for simultaneous operation during part of the 'cycle of the machine. The function of the cylinders and 8| andtheirassociated parts is to cooperate with the cylinder 56 in controlling movement of the carriages 36 and 3! and it is, to be noted that the diameters of said cylinders 86 and '8] are greater than that of the cylinder 56, whereby to overpower the latter during part of the cycle.

When the machine is at rest, that is ready I to commence its cycle of operations, the clamping members 16 and I8 are raised as shown-in Fig. 2 and the piston within the cylinder 56 is near the upper end of the cylinder but not up to its limit of movement. At the same time the members 83 and 84 are in contact with each other and the members 85 and 86 are out of contact, and the pistons which control said respective members are substantially in the lower ends of the cylinders 86 and BI. At this same time the air bags 96 and SI within the clamping members l6 and [8 are deflated.

Pressure fluid, such as compressed air, is admitted to and released from the opposite ends of the various cylinders automatically by a control unit 95. (See Figs. 3, 4 and 12.) This control unit may preferably be mounted in the base 64 of the machine and comprises a suitable oasing which encloses an electric motor 96 which, through suitable gearing 91, drives a cam shaft 98. A plurality of cams llll, I02, I83, I04 and are secured to the cam shaft 98'for rotation therewith and they are adapted to have their peripheries engage against a corresponding number of cam followers designated generally by the reference character I06.

I06 may be of' any ordinary or preferred forms and preferably they are all similar to each other and are mounted for actuation of plungers or rods I61 which extend through the upper wall of the casing and extend thereinto from a multiplicity of valves Ill, H2, H3," H4 and H5. The valves just referred to may be of the type known commercially as Quick-as-Wink and are characterized by individual casings within which plunger rods are operable to open and close connectiens between a plurality of different fluid ports which in turn are connected with appro- These came followers priate piping to the various cylinders, valves, fluid supplies and atmosphere, as. the case may be. Thus, as the cam shaft 98 is rotated by motor 96 through gearing 31, the cams'I0f-I05, inclusive, will slide the plunger rods I01 upwardly and downwardly at suitable times predetermined in the designing of the cams and thus operate the valves III-I I5, inclusive.

In order to simplify the machine drawings Figs. l-4, inclusive, the piping and valves have not been shown thereon but such piping and valves are shown diagrammatically in Fig. 12. Fluid pressure, for example compressed air at 200# per square inch, is supplied through a pipe I to the inlet port of valve III. Under suitable control of the corresponding plunger I01 the air so supplied to valve III will at times be delivered through a pipe or conduit HI and flexible branches I22 to the clamping arm cylinders 4| and 42, thus to supply pressure fluid to the lower ends of said cylinders whereby to move the clamps I6 and I8 downwardly to their clamping positions. On other occasions such air may be exhausted from the cylinders 4| and 42 through an appropriate exhaust port I23. When the cycle commences that movement of the clamping members I6 and I8 is the first'that occurs and the clamping which is thus effected is maintained until the splice has been completed. As a cushioning means the upper ends of the cylinders M and 42 are connected to a low-pressure fluidsupply line I24 which may carry, for example, compressed air at from 25 to per square inch pressure.

The valve II2 supplies pressure fluid through a conduit I25 to the air bags 90 and 9| within the clamping members I6 and I8. This pressure fluid may also be compressed air but preferably at selectively variable pressure to suit the particular splicing operations. This pressure-supply; line is indicated at I26 extending into valve I Valve II4 receives fluid pressure, such as'compressed air, at approximately 150# per square inch from a supply pipe I21 and it distributes such fluid alternately to opposite endsof the knife cylinder 66 through conduits or pipes I28 .and I20.

Valve II3 also receives pressure fluid from the line I21 and valve I I4, and it distributes such pressure fluid to the lower end of the anvil cylinder 60 through conduits or pipes I30. and I3I which, incidentally, are also connected with safety valves I32 and the regulating check valve I33. The valve I33 also supplies pressure fluid to the knife-stop cylinder 61 and to supplementary carriage-control cylinders 80 and 8|, such supply passing through pipes I35 and branch I36, regulating check valves I31 and I38 as well as the three-way valve I6,-pipe I1 and regulating check valve I8 previously mentioned.

The valve II5 also receives its supply of fluid from the tube I21 and distributes it alt ernately to the opposite ends of the primary carriagecontrol cylinder 56 through pipes I40 and MI and regulating, check valve I42.

The relative positions of the various pistons whenthe machine is at rest have already been described, and-.from such positions they are moved automatically in proper sequence under the control of the unit 95. Variations in the cams may be made for specific adjustments of parts of the machine. and the total duration of the cycle may be varied by changing the speed of the cam shaft 98. The cycle just referred to ineludes all of the steps illustrated in Figs. 5 to 11,

inclusive, and it is to be understood that all of the machine parts at the end of the cycle come to rest in the same positions from which they started.

In operating the machine the attendant merely lays the intermediate portion T3 of the unvulcanized inner tube or other stock over a suitable support I50; which is disposed above the clamping devices and then places the ends TI and T2 of such stock on top of the clamping members I5 and I1, leaving the extremities protruding therefrom. Thereafter the attendant tendant will be in no danger of being injured by the machine. If anything should go wrong he needs merely to kick inwardly a safety bar I which extends transversely across the front of the base 64 adjacent to the floor line and said safety bar, through its operative connections, will immediately interrupt the cycle of operations and return all of the machine parts to their original positions of rest, except the anvil I9 which is lowered, and the carriages 30 and 3| which are moved apart their full distance. The operative connections of the safety bar I55 may be variously arranged and modified as desired.

In the illustrated embodiment, the bar I55 is supported by thelower ends of a pair of arms I10 which are pivoted at "I, and which are connected by a link I12 to a lever, I13 disposed within the base of the machine. The lever I13 is adapt ed to actuate a master control valve "4 to move the parts to their positions of rest as above described. It is to be understood that the bar I55 and associated parts are not used in normal operation of the machine, but are provided only as a safety measure in the event that the operator should accidentally or carelessly have his hands caught in the machine.

Preferably the knives 20 will be heated by an appropriate heating element I55 which is mounted between them upon the slide 62, such heating element being supplied with electric current and thermostatically controlled at any desired temperature by a thermocouple I51 of any ordinary or preferred construction.

The abutment II may be adjusted by'means of a hand wheel I whereby to set the machine for operation on stocks of different thickness and preferably a gauge or indicating mechanism IIil is mounted in association with the adjusting mechanism for guidance of the attendant. A signal light I62 may be included in the operating circuit, it being so connected that it will receive current and be lighted at the beginning of the cycle and will continue to be lighted until the very end of the cycle. This signal light does not in any way affect or modify the operation of the machine, but is intended for the convenience of the machine attendant. A temperature-control unit I58 is also preferably used, such unit being commercially available in several different forms and being ordinarily mounted upon a wall or of the shop, not necessarily immediately adjacent to the machine. This temperature control unit, as well as the. power-supplying wires may be conveniently connected to a junction box I59 located on or adjacent to the base of the machine.

. From the foregoing description it will be evident that a novel method has been provided for splicing pieces and more particularly for splicing inner-tube stock and tread stock in vunvulcaniaed condition. Also novel mechanism has been provided for practicing the method. The method is one which produces superior resultsand the apparatus is relatively simple, efficient and conducive to economy. Obviously numerous changes maybe made in th steps of the method and in the arrangement of arts of the apparatus and the right is herein reserved to make such changes as fall within the scope of the appended claims without departing from the spirit of the invention.

What we claim is:

1. A method of splicing two portions of rubber which comprises cutting substantially obliquely the surfaces of rubber to be joined, and bringing the freshly cut surfaces together with transversely progressive contact.

2. A method of splicing two portions of rubber which comprises cutting transverse off-set surfaces on the rubber to be joined, and bringing the of rubber together of cut of the knife as it cuts through the rubber,

and forcing the freshly cut ends of the rubber into progressive mutual contact with fins of excess material at the joint so formed.

4. A method of splicing a rubber inner tube which comprises flattening the endsof the tube and holding them flat, cutting the so-held ends substantially obliquely, and forcing the so-cut ends together into progressive contact,

5. A method of splicing a which comprises completely flattening the ends 'of the tube, removing portions from the ends of the tube in such manner as to leave the ends tacky and transversely off-set, and then forcing said tacky ends of the tube together into complete contact,

6. A method of splicing a rubber inner tube which comprises completely flatteningthe ends of i the tube, cutting partly through one of the flattened walls of the tube, then offsettingthe line of 'such cut, and continuing it through the remainder of the tube, and forcing the so-cut ends A of the tube together into complete contact.

' them,

freshly cut surfaces into progressive mutual contact.

3. A method of splicing two portions of rubber which comprises clamping the rubber in flat condition with protruding ends, cutting said protruding ends with a hot knife, offsetting the line '7. A method of splicing an unvulcani'zed rubber inner tube which comprises condition, cutting partly through one wall of the slightly apart from each other without releasing continuing the cut through the rest of the tube leaving off-set portions on the cut ends, heating the so-cut ends, and forcing the ends together into complete contact sufliciently to form fins of excess material at the joint.

dorm CAMPBELL. JEROME F. RINGLEIN.

rubber inner tube clamping the Lube, moving the clamps 

